1. Technical Field
The present invention relates to an easy to open package and method for making the same.
2. Description of Related Art
Snack foods and other items are often packaged in bags formed from thin, flexible packaging films. These thin films are formed primarily of plastics, such as polypropylene and polyethylene, but can also contain metalized films, foil, paper, or oriented films. These packaging films can have numerous layers directed to achieving specific needs, but are generally formed at least in part by extrusion of a plastic layer, co-extrusion of multiple layers simultaneously, extrusion coating of another material (such as paper), and the lamination of two layers together via either extrusion lamination or adhesive lamination. In the discussions below, both extrusion lamination and adhesive lamination processes are discussed in more detail, but it is noted that any designated layer that is fed into these two processes can already be a multi-layer film formed by any of the above processes.
An exemplary film 100 for packaging of food products is seen in FIG. 1. The outermost layer 102 is an OPP layer, short for oriented polypropylene, while the innermost layer 106 is a metalized OPP or other barrier material. An oriented polymer material has been specially treated so that the long polymeric molecules tend to align in a given direction, causing the material to preferentially tear in that direction. Sandwiched between the two OPP layers 102, 106 is an adhesive such as polyethylene 104 or other adhesive. Printing for the package is done on the inside of the outer layer and becomes sandwiched between the middle and outer layers. The innermost, metallic layer 106 can itself be a layered laminate and contains a sealant layer 108 on what will be the inside, or product side, of the package. This sealant layer 108 is typically formed of a ter-polymer, composed of ethylene, propylene, and butylenes, along with the metallic layers, and provides a barrier to retain taste and freshness of the product contained therein. Other materials used in packaging are polyester, paper, polyolefin extrusions, adhesive laminates, and other such materials, or a layered combination of the above.
Once the material is formed and cut into desired widths, it can be loaded into a vertical form, fill, and seal machine to be used in packaging the many products that are packaged using this method. FIG. 2 shows an exemplary vertical form, fill, and seal machine that can be used to package snack foods, such as chips. This drawing is simplified and does not show the cabinet and support structures that typically surround such a machine, but it demonstrates the working of the machine. Packaging film 210 is taken from a roll 212 of film and passed through tensioners 214 that keep it taut. The film then passes over a former 216 which directs the film as it forms a vertical tube around a product delivery cylinder 218. This product delivery cylinder 218 normally has either a round or a somewhat oval cross-section. As the tube of packaging material is pulled downward by drive belts 220, the edges of the film are sealed along its length by a vertical sealer 222, forming a back seal 224. The machine then applies a pair of heat-sealing jaws 226 and accompanying jaw face 233 against the tube to form a transverse seal 228. Different shapes of jaw faces 233 result in different shaped seals. The transverse seal 228 acts as the top seal on the bag 230 below the sealing jaws 226 and the bottom seal on the bag 232 being filled and formed above the jaws 226. After the transverse seal 228 has been formed, a cut is made across the sealed area to separate the finished bag 230 below the seal 228 from the partially completed bag 232 above the seal. The film tube is then pushed downward to draw out another package length. Before the sealing jaws form each transverse seal, the product to be packaged is dropped through the product delivery cylinder 218 and is held within the tube above the transverse seal 228.
Although there is no one perfect package for all uses, there are a number of desirable features that manufacturers strive for in packages. One such feature is the ability to easily open the package. Consumers now must grip the package with both hands, pinch each side of the package between the thumb and fingers of each hand, and pull with sufficient force to break the seal. This can become more difficult as a consumer gets older. For example, some consumers have arthritis or have lost strength in their hands. Grasping the sides of a flexible bag and opening it as previously described may be a difficult task for them. Therefore, it is desirable to have a bag that is easier to open by hand than is available from the prior art.